Referring to FIG. 1, a turbine engine 10 generally includes a compressor section 12, a combustor section 14, a turbine section 16 and an exhaust section 18. In operation, the compressor section 12 can induct ambient air and can compress it. The compressed air from the compressor section 12 can enter one or more combustors 20 in the combustor section 14. The compressed air can be mixed with the fuel, and the air-fuel mixture can be burned in the combustors 20 to form a hot working gas. The hot gas can be routed to the turbine section 16 where it is expanded through alternating rows of stationary airfoils and rotating airfoils and used to generate power that can drive a rotor 26. The expanded gas exiting the turbine section 16 can be exhausted from the engine 10 via the exhaust section 18.
The exhaust section 18 can be configured as a diffuser 28, which can be a divergent duct formed between an outer shell 30 and a center body or hub 32 and a tail cone 34 supported by support struts 36. The exhaust diffuser 28 can serve to reduce the speed of the exhaust flow and thus increase the pressure difference of the exhaust gas expanding across the last stage of the turbine. In some prior turbine exhaust sections, exhaust diffusion has been achieved by progressively increasing the cross-sectional area of the exhaust duct in the fluid flow direction, thereby expanding the fluid flowing therein, and is typically designed to optimize operation at design operating conditions. Additionally, gas turbine engines are generally designed to provide desirable diffuser inlet conditions at the design point, in which the exhaust flow passing from the turbine section 16 is typically designed to have radially balanced distributions of flow velocity and swirl.
Various changes in the operation of the gas turbine engine may result in less than optimum flow conditions at the diffuser inlet and, in particular, can result in radially distorted flow entering the diffuser. For example, operation at an off-design operating point, e.g., part load operation or an off-design ambient air inlet temperature, may result in a radially non-uniform velocity distribution entering the diffuser. Also, redesigns of an existing engine, such as to increase the output of the engine, may result in less than optimal flow conditions at the diffuser inlet if structure controlling flow into the diffuser is not reconfigured for changes affecting flow conditions through the engine.